The present invention relates to vapor phase sterilization, and more particularly to determining the penetration of vapor phase chemical sterilants into a lumen.
Presently, vapor phase chemical sterilization is a popular option for medical devices which are temperature sensitive. Vapor phase sterilization encompasses such sterilants as hydrogen peroxide, peracetic acid, ethylene oxide and chlorine dioxide. The chemical vapor diffuses into contact with and sterilizes the surface of the instrument. Penetration of long narrow lumens with the vapor represents one of the largest challenges. Determination of whether such penetration has been successful is a further challenge. Presently, it remains difficult to place a reliable sensor in a long narrow lumen. Such sensors are typically too large to be accommodated within the lumen and their presence may disturb the diffusion into the lumen.
Although, directly measuring concentration of a vapor sterilant inside the lumen remains a challenge, several methods have been put forward for directly measuring such concentration within a sterilization chamber of such a sterilization system. For instance, hydrogen peroxide concentration can be measured by passing lightwaves of certain frequencies through the chamber and detecting the absorption of the lightwaves to determine the makeup of the gases within the chamber. In another method, a thermocouple coated with a catalyst for breaking down hydrogen peroxide can be placed within the chamber and the degree of heating caused on the thermocouple by the breakdown of hydrogen peroxide can be used to indicate the concentration of hydrogen peroxide within the chamber. Of course, other methods may also be employed to measure the concentration of hydrogen peroxide or other chemical vapors within a sterilization chamber. However, such measurements do not reveal the concentration within a lumen of a device within a chamber.
The present invention overcomes this and other limitations in the prior art and provides a method for determining the concentration of a chemical vapor sterilant within a lumen of a device within a sterilization chamber.